Philips Energy Saver Compact Fluorescent Non-Integrated (CFLni) 35 Watt PL-L 4-pin (2G11) base light bulbs are compact UVC (germicidal) bulbs used in water and air disinfection units to aid with the deactivation of bacteria, viruses and other micro-organism. The compact size of the light bulb allows for a small system design and design flexibility. Philips TUV PL-L light bulbs offer almost constant UV output over their complete lifetime, for maximum security of disinfection and high system efficacy. Featuring a single-ended base, this PL-L light bulb is easy to replace.